There are two ways you can go about getting that jail broken iPad sold without your personal info on it - one is easy, one is more difficult.
The easy way is to remove the jail break on that iPad by putting the latest iOS on it (6.0.1 at this time). You can connect it to iTunes, select "Restore" and let iTunes do it's magic. Then, when prompted by iTunes, you elect to "set up as new" (versus restore from backup). When it's all said and done, you'll have an iPad in a like-new condition as if it came right from the store. All your data and info will have been wiped with the upgrade.
That's the easy way. And, probably the best - unless one of the attractions you have for that iPad (to buyers) is that it's jail broken. Then, you don't want to remove the jail break - but you do want to remove all your data AND apps. Apple's EULA does not allow you to transfer apps, nor can you sell them or include them as part of the deal. Copyright restrictions say the only thing you can do is remove all non-default apps.
One thing, however - if you're selling it jail broken, do not select ANY of the Reset categories in the Settings app. That will muck up the jail break and you'll have to restore it to stock, thus losing the jail break.
So, to get the iPad ready for sale, remove all the apps (free ones, too), songs, movies, etc. you've put on it (iTunes will help here). Delete all your e-mail accounts. Essentially, wipe yourself and all your personal info from the iPad - everything you can think of. Oh, and sign out of iTunes, the App Store, iCloud. I'm sure I'm missing some stuff but ypur main goal is to put everything back as if it were new (but still jail broken).
This applies to Cydia, also. You'll want to remove all the tweaks you've put on it. Essentially, leave the buyer with nothing but the Cydia app.
Hope some of this helps. Good luck.
Marilyn